11.1 Introduction to Component Lead, Pin, Pad, and Termination Conditioning and Tinning

The guides in this section cover the requirements for tinning components using robotic hot solder dip systems to replace the finish on various electronic components. The objective is to ensure that robotic hot solder dipping will not lead to increased failure of electronic components after being solder dipped, and ensure a quality process is performed each time. 

There are three primary reasons to solder dip electronic components: leads, pads, and terminations.

1. Tin Whisker Mitigation
   Solder tinning for tin-whisker mitigation differs from solder dip for solderability. For tin whisker mitigation, the termination must be coated over its entire length up to the package surface. During solder dip, the piece part experiences temperature differences that are more significant than those present during typical board-level assembly. In addition, the fluxes used during the dipping process can become trapped in minor delamination, like that commonly found in plastic piece parts, leading to reliability issues. The solder dip process must be qualified and carefully controlled to avoid these concerns. Typically, tin whisker mitigation replaces a pure tin finish with a solder alloy containing various percentages of lead. Replacement finishes using alloys that do not contain lead should be evaluated for tin whisker mitigation before implementation.
2. Finish Restoration
   Solder tinning for lead, pad, and termination restoration is required when the solder finish does not meet requirements due to long-term storage or environmental exposure.
3. Reclamation and Salvage
   Solder tinning for lead, pad, and termination after component reclamation is designed to meet requirements so the components can be reused, including through the use of automated assembly equipment. In addition, during component reclamation and salvage, leads, pads, and terminations may become distorted and misaligned. Realignment to meet specifications may be required. 
   

Robotoc Hot Solder Dip
Due to the need to completely control the rates of immersion and emersion of the component terminations and the dwell times in and between each process step, robotic hot solder dip is recommended for electronic component tinning. Semi-automatic or purely manual solder dipping processes may not be capable of completely controlling the rates of immersion and emersion of the component terminations and only provide approximate dwell dipping times in the solder bath. Greater variation in the process may cause a higher chance of damage, including latent reliability problems.

Manual dipping required for full finish replacement differs from manual dipping currently practiced for meeting solderability requirements because of the increased need for 100% coverage of the component body to prevent whisker growth. Certain electronic component package styles may not lend themselves to robotic hot solder dipping and may require alternative processing. 

Note: For detailed information, refer to GEIA-STD-0006 Requirements for Using Robotic Hot Solder Dip to Replace the Finish on Electronic Piece Parts.

• GEIA-STD-0006
  This standard defines the requirements for fully replacing undesirable surface finishes using robotic hot solder dip. Requirements for qualifying and testing the refinished components are also included. This standard covers the replacement of pure tin and Pb-free tin alloy finishes with SnPb finishes for subsequent assembly with SnPb solder. This standard covers process and testing requirements for a robotic dipping process and does not cover semi-automatic or purely manual dipping processes.
• GEIA-STD-0006
  This standard does not apply to manufacturers who initially build components with a hot solder dip finish. It applies to refinishing performed by a robotic hot solder dip service supplier or production facilities at the customer's site whenever the dipping intends to have full coverage and replace Pb-free tin. Replacement of BGA spheres or CGA columns is not included in the scope of this standard. IEC TS 62647-4 may be used to replace BGA spheres.
• GEIA-STD-0006
  This standard is for suppliers and customers to incorporate these requirements into their operations to provide a consistent and well-controlled process for product applications that require significant control. Complete conversion of termination finishes from pure tin or Pb-free solder to SnPb will allow the use of electronic components for any of the Control Levels of GEIA-STD-0005-2 without mitigations. In addition to eliminating tin whisker risks, electronic components processed to this standard will exhibit enhanced solderability and joint reliability compared to most COTS finishes. 
  

Requirements for Robotic Hot Solder Dipping Apparatus
Robotic Hot Solder Dipping Apparatus shall include the following.

• Feature a vacuum or mechanical pickup mechanism
• Do not damage the piece part or its terminations
• Do not utilize metal surfaces that may scratch or cause solder smears
• Be capable of controlling the dwell time in the pre-heat and solder pot within ±0.1 seconds
• Be capable of controlling the exit speed out of the solder pot to within ±0.12 inch (0.3 cm)/s
• Be capable of controlling the depth of immersion to within ±0.004 inch (0.01 cm)
• Ensure dipping of the full termination or other tin or Pb-free tin finished surface into the solder pot, including the side of the package (if applicable)

Apparatus for Gull-Wing Formed Leads
In addition to those requirements above, the dipping apparatus used for robotic hot solder dipping gull-wing formed leads shall also be capable of edge dipping the piece parts with the following controls:

• Solder dip immersion angle and direction of travel
• Solder dip withdrawal angle and direction of travel
• Ability to rotate the piece part to allow each side to be solder dipped independently

Apparatus for J-Leaded Formed Leads
In addition to the requirements above, the dipping apparatus used for robotic hot solder dipping J-lead-formed leads shall be capable of edge and planar dipping the piece parts to cover neighboring termination surfaces not obstructed by the package body.

Overall Process Flow

1. Qualification of Process
   Before production, qualification of the refinishing process shall be performed per GEIA-STD-0006.
2. Dry Bake
   The MSL of the piece parts shall be obtained/verified/by the customer. All piece parts with MSL 2 or greater shall be dry-baked before refinishing, following J-STD-033. Dry bake is not required for electronic components received in labeled dry bags with desiccant and humidity indicators reading less than 5% RH or for electronic components Type 1. Once the packaging has been opened, it shall be handled following J-STD-033. Moisture-sensitive electronic components received in unknown conditions shall be dry-baked per J-STD-033. The cumulative bake time limits of J-STD-033 shall not apply to baking before refinishing.
3. Fluxing
   The flux used shall be per GEIA-STD-0006 or customer requirements and shall be applied to the piece parts consistently and repeatedly.
4. Preheat
   Components shall be preheated before robotic hot solder dipping. Preheat ramp-up rates shall not exceed the original piece part manufacturer's specifications, J-STD-020, J-STD-075, or as specified in engineering documentation.
5. Application of Solder
   After flux and preheat, the part terminations shall be immersed in the molten solder by a robotic hot solder dipping apparatus. The total time in solder shall not exceed 5 seconds per immersion. A dynamic wave or another method that removes solder dross shall be used.
6. Cool Down, Cleaning, and Drying Methods
   Cooling rates shall not exceed the component manufacturer’s specifications, J-STD-020, J-STD-075, or as specified on engineering documentation. Cleaning shall be performed within 1 hour of solder dipping, following the flux manufacturer's recommendations or J-STD-033 and J-STD-075, where applicable. Drying shall be accomplished to prevent the re-deposition of ionic material onto the electronic components or reduce the solderability of the component.
7. Rework
   Piece parts within the production lot shall not be reworked more than twice. A single rework process is defined as one complete throughput through the robotic hot solder dipping process for any combination of package side(s) after the initial robotic hot solder dip. Any piece parts damaged shall be segregated, marked as defective, and returned to the customer; this includes piece parts dropped into the solder pot or on the floor or exhibiting physical damage after a fall.
8. Inspection and Testing
   Electronic components shall be tested following applicable test methods defined in GEIA-STD-0006 or as defined by customer drawings. If there are any failures during applicable test methods of the production lot testing, then the customer shall be notified. Failed tested electronic components shall be segregated, marked as defective, and returned to the customer. Production electronic components of failed lots shall be identified and returned unless screened for defects in the sample devices.
9. Post-Process Baking
   After all processing and inspection, electronic components that were dry baked shall be dry baked again following J-STD-033 and dry packaged in moisture barrier bags. The cumulative bake time shall be reset to "zero" upon final packaging.

Straightening Component Leads
Straightening and realigning leads on QFP, gull-wing, J-lead, and other leaded surface-mount or through-hole components that are bent, twisted, or otherwise misaligned may require adjustment before reuse by manual soldering and automated machine placement. A variety of tools may be required, including fine-tip smooth jaw pliers, lead-forming tweezers, and component lead alignment template/fixtures.

Before adjustment, perform a visual inspection to identify all leads for bends, twists, or displacement from the normal seating plane. The lead straightening procedure should reposition any misshapen leads without stressing the leads. Using smooth jaw pliers or lead-forming tweezers, lightly bend the misaligned lead toward its original position in small, controlled increments. Avoid large deflections that can fatigue the metal. If a lead is twisted, rotate gently at the tip while supporting near the heel to prevent stress on the package body. After each adjustment, check lead coplanarity and pitch against a lead alignment gauge. Ensure all leads rest on the same seating plane within IPC-610 tolerance (typically ≤0.10 mm gap). Verify that lead spacing matches the component specification. If required, clean with approved solvent and a lint-free wipe to remove oils from handling. Allow to dry before further processing.